1. Field of the Invention
The present invention concerns a device particularly suitable for propelling an in-line skater by harnessing the energy of air currents. More particularly, the invention concerns a device which is particularly effective in harnessing and transmitting air current energy to an in-line skater in a controllable, simple, and intuitive manner. The device is simple to construct, rugged and durable, and safer to use than conventional sail devices. The device is easily disassembled and in the disassembled state assists the skater to return to an upwind starting position.
2. Description of the Prior Art
In-line skating, also known as roller blading, is a popular recreational activity. As compared to roller skates, wherein four wheels are distributed around the four corners of the foot providing a stable platform, in-line skates have wheels arranged in a line. Due to this wheel configuration in-line skates are more maneuverable than roller skates, but at the same time are more unstable and require greater ankle strength and skill to use.
The increase in popularity of in-line skates has spawned an increase in developmental activity leading to a variety of improvements or refinements as evidenced by, e.g., U.S. Pat. No. 5,382,052 for an in-line roller blade figure skate and U.S. Pat. No. 5,239,941 concerning a braking system for in-line roller skates. Further evidencing the popularity of roller blades is the "roller boot" described in U.S. Pat. No. 5,507,506 comprising a boot and a wheel frame wherein the wheel frame can be detached from the boot and the boot can be used for walking.
While in-line skates were primarily designed for the recreational and exercise benefit of the skating activity, experiments have been made to use in-line skates as a basis for short distance transportation, including attempts to connect propulsion means to in-line skates. For example, small motors have been coupled to one of the wheels of an in-line skate whereby a skater can be propelled along level ground at speeds of up to 20 mph. However, such a device has many disadvantages. Any mechanical device is prone to mechanical failure. Motors containing flammable material may not be allowed indoors or near flames. Motors require servicing including filling with gas. The range of transport depends upon the amount of fuel carried. The attachment of a heavy motor to an in-line skate renders the skate bulky such that the in-line skates can not be used in a normal manner. Further, the mounting of a motor is not a simple matter, requires special hardware and adaptations, and can not easily be removed. A motor based system for an in-line skate is relatively expensive. Parents would not consider this system safe for children, considering the speeds achieved and the likelihood of meeting traffic. The two-stroke motor exhaust fumes are offensive to those desiring the benefits of fresh air while exercising. Accordingly, the motorized approach to propelling skates has not met with commercial success.
The relatively low power and endurance of an in-line skater is particularly challenged on windy days, especially when the skater is attempting to skate into the wind. Accordingly, in-line skaters tend to skate on days where skating is not hampered by wind. This limits the number of days during which skates can be used, which may be a problem in windy regions.
Another problem with in-line skates is that it is easy to become hot and fatigued. Thus, a means of propulsion which would not exhaust the skater, not pollute the atmosphere, and help keep the skater excited yet cool, would be welcome in this sport.
Accordingly, there is a need for an external propulsion device for a in-line skater. There is also a need for a device which enables an in-line skater to skate on windy days. There is also a need for a new device which can be associated with in-line skating and which would greatly enhance the enjoyment of in-line skating, particularly on windy days.
In view of the above, the present inventor desired to propel himself using air currents, and undertook investigation into prior art attempts to harness the energy of air currents to skiers, skaters, or skateboarders. The inventor soon realized that, given the differences in the way energy is transmitted through the human body to in-line skates and the manner in which sails have previously been connected to the human body, the known methods of harnessing air currents are unsuitable for application to in-line skating.
For example, U.S. Pat. No. 3,982,766 teaches a wind-propelled skateboard including a skateboard for transporting a skateboarder, a mast which is detachably coupled to the body of the skateboard in such a manner that it is substantially free from pivotal restraint, a boom coupled to the mast by a hinge, and a triangular sail coupled to both the mast and the boom. This inventor essentially adapted the sail from a wind surfer (a wind propelled surfboard) to a skateboard. However, such a design cannot be adapted to in-line skates for a number of reasons. First, the skater does not have a stable platform to which to attach a sail. Attaching a mast of a sail to only one of two in-line skate boots would put significant downward pressure on that skate, rendering the skater incapable of skating or maneuvering in a normal manner. Second, the variation in pressure applied to a sail by an air current would cause the in-line skate to which the sail is attached to be either pulled out from under the in-line skater in the case of a gust of wind or, in the case that the in-line skater is moving at a substantial speed and leaning backwards to counteract the effect of the pulling against the skate by the sail, a sudden loss of air current would cause the in-line skater to fall backwards, possibly injuring himself.
U.S. Pat. No. 4,130,292 to Lorenz teaches a more complex apparatus for propelling a skate board using air currents. A central upright mast is attached to a swivel base plate, a sail is draped from a horizontal cross-tube affixed to the top of the mast, and two booms with handles are attached to the swivel base plate such that the skate boarder can hold onto the two handles and maneuver the sail while skating. Obviously, such a complex system is completely unsuitable for adaptation to in-line skating. Further, such a complex sail design cannot be easily dismantled, disassembled and transported such as when moving from a downwind position to an upwind position.
U.S. Pat. No. 4,978,140 (Babson) teaches a hand-held skate sail which appears to be somewhat simplified over that shown in Lorenz. Basically, a fan shaped sail radiates outward from a base plate affixed to the skateboard. Such a sail would be completely unsuitable for an in-line skate application since the air currents would have to pass through the body of the in-line skater to impact upon a sail. Since this sail is designed to redirect the flow of air currents directly upwards, this arrangement would be completely inefficient and unworkable when considering an in-line skate application.
U.S. Pat. No. 4,489,957 (Holmgren) teaches a tool for sailing with skates, skis, roller skates, skateboards or corresponding gear. According to Holmgren respective ends of a carrier bar are fastened to the sailor's feet. While this device would enable a rather large mast to be attached to a skater, a significant number of obvious disadvantages render this design unsuitable for adaptation to in-line skates. First, the shackling of a transverse member to both feet removes a large amount of control from the in-line skater rendering the sport more dangerous. Second, the in-line skater, having achieved a substantial forward momentum, cannot easily steer this device or stop when approaching an obstacle. In the case that the in-line skater having such a sail attached to his feet panics and drops the sail, the skater would immediately stop due to jamming of the sail under the roller blades or else would drag the sail on the ground. In either case, the sudden deceleration at the base of the in-line skater would cause the in-line skater to fall forward and likely injure himself.
U.S. Pat. No. 4,204,694 (Freeman) teaches a sail apparatus for propelling a moveable body such as a skate, ski, an ice boat or the like. An upper spar and lower boom are used to hold a triangular shaped sail in an open triangular form. The mast is connectable to the spar end boom for supporting the sail above the moveable body. The bottom of the mast is detachably coupled to the transport body in such a manner that the mast may be articulated with respect to the body in any direction. However, one problem with such a device is that the sail must be in close proximity to the human body, thus the body of the sailor blocks the air current and diminishes the effectiveness of the sail. A further disadvantage is that, in the case of propelling skates or skis, the sail must be attached to the human body by a harness as shown in FIG. 4 of this patent. The direct coupling of the sail to the human body increases the danger of the sport in that the sailor cannot readily disengage himself from the sail in the case of an imminent collision. A further problem is that the sail is directly connected to, and places significant downward pressure, on one foot of the sailor, thereby impeding mobility of that ski or skate. Finally, this device is complex to use, requires education and experience, and is relatively complex in its construction.
U.S. Pat. No. 4,269,133 (Brown) teaches a hand-held sail having a unique design and capable of propelling a skater across a horizontal surface. The sail is essentially a "delta" sail with a central transecting boom, the boom including a U-shaped projection which can be grasped by the sailor. A harness formed by a strap is attached to the U-shaped portion and looped around the neck of the sailor. However, on consideration, it can be seen that such a device is inefficient as a means of propelling a skater for two main reasons. First, the requirement to transmit the horizontal propelling forces generated in the sail horizontally through the neck and shoulder of the sailor, then perpendicularly downward through the length of the body, then perpendicularly to the skates, requires a great amount of muscle tone, coordination, concentration and provides the least amount of control, particularly in variable winds. Second, the requirement to place the sail directly downwind of the sailor renders the sail inefficient as a device for capturing air currents.
U.S. Pat. No. 4,311,324 (Fries) teaches a sail device for use in propelling a roller skater, ice skater or the like. The device appears to be easy to operate in that it employs a balancing pole, with the sail being suspended between the balancing pole and the individual skates. Therewith the propulsion forces of the wind are efficiently transmitted in part to the arms and in part directly to the feet, and the balancing pole helps the skater maintain balance. However, a significant disadvantage with this system is that the balancing pole projects outwardly a great length on either side of the skater, such that the device can only be used where there is a board clear path. Further, while the balancing pole increases stability of the sailor against falling down, it diminishes the ability to turn. Further, while the low center of gravity of the sail area reduces leverage against the sailor and thereby increases stability, air currents are greatly reduced near the ground, so this configuration requires a large sail area to capture diminished air currents. Another problem is caused by the combination of the heavy weight of the balancing pole and the fact that the sailor must apply constant upwards pressure on the pole to keep the sail taught and capture wind. This requirement to constantly pull upwards on the balancing pole will soon tire the sailor. Further, sails provided downwind of the sailor have air currents blocked by the body of the sailor, and this arrangement has a particularly high amount of blockage. Thus, such a sail arrangement is very efficient. Further, since the sails are fixedly attached to the skates of the sailor, the sailor can not stop or disengage from the activity by simply dropping of the sail, since this would result in the sail tangling or acting as an anchor to the skates, causing the sailor to fall forward. Finally, once the skater has allowed themselves to be pushed downwind, there arises the problem of how to return upwind, carrying the balancing pole and sail. It can thus be seen that what may at first glance looks like a good idea does not translate into a workable sail device.
Accordingly, what is needed is a new device which would enable an in-line skater to more effectively harness air currents. In order to have great practical and commercial appeal, the device must be relatively simple, rugged, durable, and safe, i.e., it cannot be directly attached to the sailor by means of harnesses, buckles or other attachment means. What is needed is a device for propelling an in-line skater which can be easily controlled and maneuvered so long as the sailor feels comfortable, and can be completely released and disengaged from when the sailor sees imminent danger.
Further yet, there is a need for a device which is intuitively much easier to operate than the above described devices, and which optimizes the leverage forces between the wind current, sail, mast, sailor body and mast attachment point.
Finally, there is a need for a device which can be used not only to propel the skater downwind, but which also assists the skater to return to the upwind starting point, thereby completing a cycle of use.